How to Control Active Timeouts in Javascript: Pausing, Resuming, and Retrieving Remaining Time

Controlling Active Timeouts with Javascript

Managing active timeouts in Javascript is often necessary for various applications. One may encounter situations where pausing and resuming a running timeout is desired. Additionally, obtaining the remaining time on a current timeout can be useful in certain scenarios.

Pause and Resume a Timeout

To pause an active timeout, one can utilize a wrapped version of window.setTimeout. This wrapper introduces a Timer class that provides pause and resume methods. Here's an example:

<code class="javascript">var Timer = function(callback, delay) {
    var timerId, start, remaining = delay;

    this.pause = function() {
        window.clearTimeout(timerId);
        timerId = null;
        remaining -= Date.now() - start;
    };

    this.resume = function() {
        if (timerId) {
            return;
        }

        start = Date.now();
        timerId = window.setTimeout(callback, remaining);
    };

    this.resume();
};</code>

To use this class, create a Timer instance and pass in the callback function and delay as arguments. Then, use the pause and resume methods as needed.

Get Remaining Time on Timeout

Unfortunately, there is no native way to obtain the remaining time on a current timeout in Javascript. However, you can emulate this functionality by storing the current timestamp when the timeout is set and then calculating the remaining time by subtracting this timestamp from the current time.

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